1. Field of the Invention
This invention relates to asphaltic compositions and, more particularly, to asphaltic compositions characterized by improved thermal stability and bright appearance.
2. Description of the Prior Art
It has heretofore been known to use asphalt binders for road building and various other industrial applications. Such products, however, have exhibited poor elasticity, thereby limiting their use in fields requiring supple and high mechanically resistant products. In order to increase the desired elasticity, it has been proposed to incorporate various additives in the asphaltic composition, such as copolymers of ethylene and vinyl acetate, as more particularly described in U.S. Pat. No. 3,442,841. While the addition of ethylene-vinyl acetate copolymers imparted increased elasticity to the resulting asphaltic compositions, it also unfortunately provided products exhibiting poor cohesion (i.e. stress necessary for a given deformation) and weak adhesiveness.
To enhance the latter properties while retaining desired elasticity characteristics, it has been proposed to provide an asphaltic composition comprising a major amount of straight-run asphalt, a minor amount of a copolymer of ethylene and vinyl acetate and a minor amount of a synthetic terpenic resin. Such compositions, which are the subject matter of U.S. Pat. No. 3,821,144, while providing distinctly improved products, have been lacking in desired thermal stability and appearance, with a dull surface haze characterizing the asphaltic compositions so produced.
In copending application Ser. No. 673,171, filed Apr. 2, 1976, now U.S. Pat. No. 4,064,082 there are disclosed asphalt compositions comprising a major amount of road (straight-run) asphalt and minor amounts of thermal asphalt, ethylene-vinyl acetate copolymer, and a terpenic resin. Such compositions evidence good heat stability, but, however, thermal asphalts are obtained from thermal cracking units. These units, widely used prior to World War II, have been largely replaced by catalytic cracking units which do not yield asphalt components as such.